It’s probably a cashier’s check from the bank or institution that managed Denny’s trust fund.
And honey is that a guess or do you have you traveled from the future to fill us in?
It’s from a very reliable spoiler source.
The casting sides (at showfax.com) show McDreamy’s sister in that scene. Then later at the hospital she says something insulting in front of Meh which McDreamy asks her to apologize for. There are people at Televisionwithoutpity who subscribe to the sides and go over every role and scene with a fine tooth comb. I swear these people spend hours a day at it.They’ve always been spot on in the past so I trust them completely.
I was a complete geek and thought, but she’s got to find 87 different banks to go to to protect the money under FDIC limits.